The definitive-base package

The Definitive framework is an attempt at harnessing the declarative
nature of Haskell to provide a solid and simple base for writing
real-world programs, as well as complex algorithms.

This package contains the base modules of the framework, and provides
only the most basic functionality, ranging from basic algebraic
structures, such as monoids and rings, to functors, applicative functors,
monads and transformers.

Lenses are used heavily in all the framework's abstractions, replacing
more traditional functions (WriterT and runWriterT are implemented
in the same isomorphism writerT, for example). When used wisely,
lenses can greatly improve clarity in both code and thought, so I
tried to provide for them in the most ubiquitous way possible,
defining them as soon as possible. Isomorphisms in particular are
surprisingly useful in many instances, from converting between types
to acting on a value's representation as if it were the value itself.

Packages using the Definitive framework should be compiled with the
RebindableSyntax flag and include the Definitive module, which exports
the same interface as the Prelude, except for some extras.
Here is a list of design differences between the standard Prelude
and the Definitive framework :

The +, -, negate, and * are now part of the Semigroup,
Disjonctive, Negative, Semiring classes instead of Num (default
instances are defined to reimplement the Prelude, making it easy
to adjust your code for compatibility)

The mapM, traverseM, liftM, and such functions have been hidden,
since they only reimplement the traverse, map, and other simpler
functions.

Lenses are used whenever possible instead of more usual functions.
You are encouraged to read the interface for the Algebra.Lens
module, which contains everything you will need to be able to use
lenses to their full potential (except maybe a good explanation).